Likely, your answer is carbs, like starches, fruit, and other sugars.
When you walk, or talk, or simply move through your daily routine, you are burning energy, and typically most people get their energy from Dietary Carbohydrates
Much of the time, especially with the modern-day heavy-carb diet, your energy comes from carbohydrates. These are sugars and starches, which are broken down into glucose, which is then used by the body for energy.
Unfortunately, excess glucose that is not fully used as energy converts to glycogen which is then stored as fat.
“Carb overload” is believed by many experts to be the #1 cause for overweight and obesity today.